Steering angle sensors for determining the absolute value of the steering angle are known in a wide variety of embodiments. In addition to identifying multiple revolutions by means of a gear mechanism or using a magnet arrangement which identifies multiple revolutions independently of the supply voltage, steering angle sensors in which the absolute value of the steering angle is determined by means of an optical arrangement are also known. For example, DE 100 41 507 A1 discloses a steering angle sensor for motor vehicles, in which steering angle sensor a code track is provided on one of two assemblies which can be rotated relative to one another, and in which steering angle sensor a detection device for scanning the code track is provided, this detection device being associated with the other assembly and generating a signal, from which the steering angle can be determined, when the code track is scanned.
This steering angle sensor has the disadvantage that, although a steering angle is always identified provided that the steering wheel is no longer being turned as a revolution, it is only possible to identify a multiple revolution for as long as the supply voltage is connected. If this supply voltage were disconnected, for example when parked, this steering angle sensor is thus no longer in a position to identify the actual number of steering wheel revolutions after the ignition is switched on.
The absolute optical angle sensor of DE 197 58 104 A1 also exhibits this disadvantage.